10 Things to Know About the Flu

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The flu is in the news a lot these days, but how much do you know about it?

1. What is it? The flu, aka influenza, is an RNA virus that attacks the respiratory tract. It is not related to gastroenteritis, which is sometimes called “the stomach flu.” This virus happens to be highly contagious, spreading rapidly through airborne particles from patient to patient, and it can cause serious complications.

2. What are the symptoms? The flu often feels like a garden-variety cold. You may feel sniffly and stuffed up, and you could develop chills and a mild fever. Sore throat and runny nose are common as your nasal passages generate mucus, and you may start coughing because your body will want to try to expel mucus so it doesn’t reach the lungs. Body aches are also common with the flu, an indicator that your immune system is hard at work. Some patients also notice swollen glands, another sign of increased immune activity.

3. What should I do if I get it? For the vast majority of patients, the recommendation is rest and fluids, especially warm ones like soup and herbal tea. If, however, you start to develop a fever above 102, chest pain, rapid breathing, difficulty breathing, coughing, or an altered level of consciousness, you need to see a doctor. You should also see a doctor if you are pregnant or have a history of lung problems. Your doctor’s office may ask you to put on a mask before entering and use a side door to protect other patients if there are concerns about spreading the flu.

4. How do flu shots work? Vaccination is one of the more impressive developments in medicine, designed to confer immunity by exposing patients to a specially treated form of a virus so they can develop antibodies. In the case of flu vaccines, a dead virus is used, which is very good news for you: you can’t get the flu from the shot, because there’s nothing living in the vaccine. Once you get the shot, your immune system will recognize the flu proteins in the future and it will go on the offensive. Since flu strains change each year because the virus is constantly evolving (more on strains below), you need to re-up your vaccine annually for it to be effective.

5. Do I really need a flu shot? Recommendations about flu shots vary by nation and agency. If your doctor recommends a flu shot based on your medical history, you probably need one, although you can discuss the risks and benefits to decide if it’s the right choice for you. If you’re over 65, you should get one. If you’re older than six months, you might need one if you have a kidney, liver, heart, or lung disorder, and also if you’re pregnant, immunosuppressed, or have diabetes. Getting a flu shot doesn’t just protect you. It also contributes to herd immunity, which helps to protect the most vulnerable members of the population, like those babies who can’t get vaccines because they’re too young.

6. What are flu “strains”? The influenza virus is a rather complex little guy, given how tiny it is. It’s not a single virus, but actually a whole family broken into a number of genera and species; the most important for our purposes are influenzas A, B, and C. Each species is further broken down into serotypes on the basis of the proteins found on the surface of the virus. If that sounds like gobbledygook to you, don’t worry: think of serotypes like an individual virus’ “signature.” These proteins act as antigens, which makes them important because they are what the body reacts to when flu viruses enter the body. Officially, they’re known as hemagglutinin and neuraminidase, which is why you’ll see flu referred with terms like H1N1 and H3N1 to describe different strains.

Different strains react to treatment differently, and doctors may test a patient because this can help with making treatment recommendations, while researchers want to track the spread of flu by noting which strains show up and where. This information is also useful for the development of flu vaccines, which are based on predictions of which strains will be likely in a given year.

7. What are swine and avian flu? Swine and avian flu, other than media stars, are specific types of flu that originate in pigs and birds. They, like many other animals, can be infected with influenza viruses, but these usually don’t cross species. Sometimes, very rarely, a virus makes the leap from pigs (or birds) to people, usually those in close contact with infected animals. Typically it stops there, often without any active infection at all, but sometimes, even more rarely, it spreads through the human population. The notorious 1918-20 flu is believed to have originated in pigs, and involved a particularly lethal strain that had optimal conditions, from the point of view of a virus: World War One had large numbers of people moving around a lot and spending time in crowded conditions.

8. How come there’s a flu season? Flu always seems to strike when you’re already feeling low: during the cold, dark winter months. There’s a reason for that; this highly contagious disease spreads readily in confined spaces where people are crowded indoors, a common problem in the winter, where no one really wants to be outside, and windows aren’t open for ventilation because it’s too cold.

9. Is influenza really fatal? It can be, depending on the strain and the patient. Some strains are very aggressive, while others are weaker. Very old and young patients, as well as those with compromised immune systems, can be at risk of death. Fortunately there are a number of treatments available to help flu patients, including medications and monitored care in the hospital if necessary. The big concern is that the flu can turn into pneumonia, which can potentially be very dangerous, especially if a patient has a history of respiratory problems.

10. I heard it’s an epidemic, should I panic? No! You shouldn’t. “Epidemic” sounds scary, but it’s a reference to the incidence of the disease in the general population. An epidemic is an outbreak (some epidemiologists — people who study disease — use the terms interchangeably) of disease that is higher than expected, and higher than the background rate. In other words, more people are getting the flu than usual (if you’re a nerd, you can check out Google’s flu trends for interesting real-time flu data). It’s only when it becomes a pandemic, meaning that it has spread across a wide area, that you need to worry. But please, don’t panic! The CDC and other agencies have plans in place for dealing with outbreaks, and they need you to stay calm.